Copper-beryllium alloys



Patented Feb. 18, 1936 COPPER-BEBYIJJUM ALLOYS Werner Hessenbruch,Hanau-on-the- Germany, assignor to Heeus-Vacuumschmelse,

ermany No Drawing. Application June 15, 1934, Serial N0. 730,727. InGermany June 17, 1933 2 Claims. (Cl- 75-1) This invention relates toimprovements in copper beryllium alloys. Its nature, objects andadvantages wlll be best understood from the 101- lowing.

5 If one adds to copper about 3.0% beryllium, one gets alloys improvableby heat treatment, which, after quenching at about 750 C. and subsequentheating to about 250 C. to 350 C., show a sharp increase of hardness andof other mechanical properties. I These alloys have, how-'- ever, thedisadvantage that on account of the high beryllium content their priceis so high that frequently they cannot be produced economically.Furthermore, the binary alloys of' copper and berylliumshow phenomena ofsoftening if the temperature necessary for heat treatment is maintainedfor a substantial period, the softening occurring because the beryllidsegregates and agglomerates in certain places. Cold working, in

:0 addition, introduces the detrimental influence of re-crystallization.The net result is that heat treated pieces or parts assume, after ashort time, a comparatively considerable hardness but lose this hardnesson remaining a certain time at a temperature of from about 300 C. to 400C.

I have discovered that this softening may be overcome and that also theamount of beryllium for a determined hardness may be reduced. I obtainthese results by adding titanium, which will 80 alloy with the copperbut decreases the solubility of the beryllium in the solid copper, i.e., by decreasing the amount of alpha mixed crystals. Experiments haveshown that nearly all additions of other elements to copper berylliumdecrease the'territory of the alpha-mixed crystals with the exception ofnickel.

Aside from thus influencing the territory of the mixed crystals, theaddition of titanium increases the crystallization temperature so thatwith such 40 alloys the danger of the softening is considerably lessthan with the binary copper-beryllium alloys.

Extensive investigations with many various additions have shown that thebest results with respect to improvement by heat-treatment can beobtained by employing titanium which, by itself,

is able to form copper alloys improvable by heat treatment. Nickel, thealkaline metals, the low melting metalloids and the noble gases,apparently are not suitable. 5.

The surprising efiect of additions of the character above described isshown by the following examples. If one adds about 1% of beryllium tocopper, heat treatment of 350 C. has practically no effect. The criticalhardness oi Brinell 10 rises only to Brinell in 14 hours. If one adds tothe copper, in addition to the 1% of beryllium, for instance 3%titanium, .the hardness after heat treatment of about 10 hours rises to260 Brinell. If one starts with a hard worked piece 15 of this alloywhich before had already to 200 Brinell, the hardness by heattreatmentup to 1350 C. rises to about 280 to 300 Brinell and remains constanteven for a long time. By more cold working it is even possible to stillincrease 2 the intial hardness without disturbing the efiect of the heattreatment on account of recrystallization.

I prefer to employ beryllium in substantial amounts above a trace up to2.5%, although I 25 may go as high as 3%. i

I prefer to use titanium in a range of from about 0.5% to about 8%. Thismetal will alloy with copper but tends to reduce the solubility ofberyllium in the copper on heat treatment, which 30 gives the bestresults.

The copper in all cases should be the base metal of the alloy and shouldconstitute above 50% of the total;

1. An alloy consisting of beryllium in quantities in excess of a traceup to about 3%, titanium from about .5% to about 8%, and the balancecopper.

2. An alloy consisting of beryllium in quantities 40 in excess of atrace up tc about 3%, titanium in an amount about 3%, and the balancecopper.

WERNER HESSENBRUCH.

